Metal-to-Nonmetal Transition inn-Type Many-Valley Semiconductors

Abstract

We have calculated the critical donor concentration n, for the Mott transition in many-valley semiconductors. Our accurate numerical solution of the Schrodinger equation for Mott s model, as extended by Krieger and Nightingale, shows that previously reported good agreement with experiments has been in part the fortuitous result of calculational simplifications. We also find that the model predicts values of n, '~3aH (where aH is the effective Bohr radius in the material) over 45/o larger in single-valley semiconductors than in Ge and Si (four and six valleys, respectively) and suggest such experiments as further meaningful tests of the model.

Semiconductor-Metal Transition in Many-Valley Semiconductors

“…Each approach gives different values for the Mott constant. For example, while the numerical integration yields 0.412, variational methods yield 0.317 [13]. It is therefore clear that even a more reasonable function with exchange and correlation effects included (Hubbard-Sham, for example) yield poor results.…”

“…A very similar distribution was considered in the numerical work of Ref. [13]. Then the potential seen by an electron due to a random distribution of impurities is given by…”

“…Interesting results on conductivity, specific heat, dielectric properties, optical phenomena and the nature of the transition with randomness in impurity distribution have been obtained [8,9]. The second approach is a one-electron approximation with manybody effects introduced in the potential energy [12,13].…”

“…It has been shown that when better dielectric functions like the Hartree function or its extensions including exchange and correlation are used, or the Schro È dinger equation is solved numerically, one gets results better than those obtained with the TF screening [13,14]. The results obtained by different groups differ starting from a value 0.2 to 0.41 for the Mott constant.…”

Efeitos de correlações e excitação de plásmon em estruturas semicondutoras

“…I : b - [14] c - [18] d - [16] e - [19] f - [22][23][24][25] SERVICO DE BIBLIOTECA V(y,z), e quase livre na dire9ao do fio quantico (GaAs) com vetor de onda k=(k ,0,0). 0 potencial do fio quantico, e em principio, x originario da solU9ao autoconsistente das equa90es de Schr6dinger…”